(CNN) -- A massive magnitude 8.8 earthquake rocked Chile early Saturday, killing at least 78 people and triggering tsunami warnings for the entire Pacific basin.

Chilean President Michelle Bachelet said she expected the death toll to rise.

"We are taking all the necessary measures at this time," she told reporters.

The full extent of the damage was not yet known, although there were reports of collapsed buildings and hundreds of people in the streets.

The capital of Santiago lost electricity and basic services including water and telephones. Bachelet said regional hospitals had suffered damage; some were evacuated. A major bridge connecting northern and southern Chile was rendered inoperable, and the Santiago airport was shut down for at least the next 24 hours.

Chilean television showed buildings in tatters in Concepcion, with whole sides torn off. Roads in the city were broken up.

Television Nacional de Chile reported that only three stories of a 15-story building remained standing.

Numerous aftershocks -- including one of magnitude 6.9 -- were felt within hours of the initial quake, the U.S. Geological Survey said.

"There are really aftershocks like every hour," said Felipe Baytelman, speaking to CNN from Santiago.

The quake's epicenter was located off the coast of Maule, about 200 miles southwest of Santiago. It struck at 3:34 a.m. (1:34 a.m. ET), when most people were sleeping.

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